Effects of treatment with single oral doses of naproxen or ATB-346 on knee joint swelling secondary to CGN-induced synovitis in rats. CGN-injected animals were orally pre-treated with naproxen (at 0.3, 1, 3 and 10 mg/kg; n = 8), equimolar ATB-346 doses (0.48, 1.6, 4.8 and 16 mg/kg; n = 8) or vehicle (1 ml/kg; n = 8). A separate control group (Sham - S) received only an i.art. injection of saline injection (n = 5). The bars represent the mean ± SEM values of the increases in articular diameters (in mm) measured 1, 3 and 5 h after CGN injection. **P < 0.01 and ***P < 0.001 vs. vehicle-treated (V) group; ###P < 0.001 vs. S; ϕP < 0.05 and ϕϕϕP < 0.001 vs. the corresponding equimolar naproxen dose, as analysed by one-way ANOVA followed by the Bonferroni's multiple comparison test.